There are many occurrences wherein it is desirable to optically couple two or more optical fibres to each other. For example. In optical amplification, a signal fibre carries a signal and is optically pumped using laser light having another wavelength to amplify the signal. To that effect, the laser light coming from the pump fibres is carried into the signal fibre and thereby provides the power required to amplify the signal circulating in the signal fibre.
Many techniques are available for optically coupling optical fibres to each other in this manner. For example, in one such technique, the optical fibres are stripped of their sheath and heated while positioned substantially adjacent to each other until the pump fibres are fused and optically coupled to the signal fibre. This involves deforming the pump fibres until they achieve a shape suitable for optically coupling to the signal fibre.
However, coupling the pump fibre typically occurs by deforming to a relatively large extend the pump fibre around the periphery of the cladding of the signal fibre. This creates surface tension problems that result in power losses. Since it is desirable, in many instances, to pump relatively large power into the signal fibre, these power losses may heat the optical fibres and eventually lead to failure of the optical amplifier. In addition, these methods for manufacturing optical amplifiers and other devices in which optical fibres are optically coupled to each other are relatively difficult to perform and it is relatively difficult to achieve reproducible results using these methods.
Another manner of optically coupling pump fibres to a signal fibre involves the use of a signal fibre having a relatively large diameter. Then, the pumped fibres may be axially coupled to the cladding of the signal fibre which is then deformed to achieve a shape suitable for guiding the light carried by the pump fibres into the core of the signal fibre. Once again, these methods for manufacturing optical fibres are relatively complex to implement. Also, they may lead to the creation of stresses within the coupled assemblies, as there is typically a need to handle the optical fibres and attach them to supports for packaging purposes.
U.S. Pat. No. 7,539,377 issued to Gonthier on May 26, 2009, describes multiple ways of fabricating fiber optics combiners usable for example for signal feed-through using a coupling piece. However, the through (or signal) fibre is coupled to the combiner in the middle of a bundle of input (or pump) fibres. This creates difficulties in assembly of the resulting component in many configurations.
Against this background, there exists a need in the industry to provide an improved methods and devices for optically coupling optical fibres. An object of the present invention is therefore to provide such methods and devices for optically coupling optical fibres.